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Arthropoda
- Insecta HEMIPTERA: Cimicidae (Bedbugs) (Contact) Please CLICK on
Image & underlined links for details: Included in
the family Cimicidae are two common species that feed on humans. Cimex
lectularius occurs in both tropical and non-tropical areas,
whereas Cimex hemipterus is not as
common in the Americas. Service
(2008) noted that the distinction between these two species is difficult, but
usually the prothorax of C. lectularius is 2 1/2 times as wide as long, while
in C. hemipterus it is narrower
or about two times as wide as long.
The abdomen of C. lectularius
is also more rounded. Other
geographically restricted species are, Leptocimex
boueti in western Africa.), and Cimex pilosellus Horvath, C. pipistrelli (Jenyns), Oeciacus spp., Cimexopsis nyctalis List and Haematosiphon
inodorus (Duges) at other world
sites. APPEARANCE Bedbug adults
are wingless and flattened dorsoventrally.
Their size averages about 5-7 mm long. The head is short and broad and has a pair of prominent
compound eyes in front of which is a pair of 4-segmented antennae. The proboscis is thin and usually held close
to the body underneath the head and prothorax. The prothorax is larger than the meso and metathorax, and
possesses winged expansions.
Hemelytra are present, which have no function. Legs are well developed and slender. Eight
abdominal segments are visible even though there are eleven. The male abdomen is more pointed than the
female. Service (2008) noted that
females have a small incision ventrally on the fourth abdominal segment,
which opens into a pouch called the mesospermalege or the Berlese Organ. It is used to store sperm after
mating. Both sexes draw blood from
their hosts. LIFE CYCLE Bedbugs draw
blood from their hosts primarily at night, but if stressed will do so also
during daytime. The bugs usually
retreat to hiding places when they are finished feeding, and thus do not
often remain in contact with people.
Their hosts include rodents, bats and birds when humans are
unavailable. Both adults and nymphs
are inactive during daytime hiding in dry cracks, furniture ceilings,
wallpaper, mattresses, etc. They
resume activity at night but will return to hiding places after blood meals. Bizarre
indeed is the mating procedure among the Cimicidae, which was explained by
Service (2008). Males penetrate the
integument to incorporate spermatozoa in a "Berlese Organ" that is
located on the female's ventral part of the abdomen. Subsequently the spermatozoa pass into the
haemocoel (body cavity) from which they gain access to the oviducts and eggs. The female
lays three or less eggs per day in building crevices and furniture if the
temperature is above 13 deg. Centigrade.
The 1-mm. long eggs are white or tan, slightly curved and covered with
a mosaic pattern. Female longevity
varies from a few weeks to months and even years. They can lay up to 500 eggs in a lifetime. Hatching depends on temperature but vries
from eight to eleven days. Eggs that
have not hatched may survive for three months. Hatching produces the nymphs, which like lice resemble the
adults. In this hemimetabolous cycle
there are five nymphal stages, each being able to draw blood. The duration of the nymphal stages varies
from two to seven weeks but again may be longer at lower temperatures. Living
bedbugs are easily detected as well as by the casts left by the nymphs during
moults. Wherever they roam they leave
tiny dark colored marks, such as on the beds and walls. There is also an undesirable odor in
dwellings where there are high infestations.
They tend to remain in single dwellings without much dispersal. Spread is frequently with infested
furniture. MEDICAL IMPORTANCE Hepatitis and
other pathogens have been recorded in bedbugs (Mayans et al. 1994), but
vectoring infections to humans is not substantiated (Service 2008). However, their presence causes distress
even though there are few reactions from their feeding activity. Because they draw blood high infestations
can result in iron deficiency in some young and older people especially. CONTROL Repellents
and the use of pyrethrum coils afford protection, but insecticidal sprays are
required for structures and furniture in case of heavier infestations. Service (2008) also noted that insect
growth regulators have sometimes been used for control. = = = = = = = = = = = =
= = = = = = = = Key References: <medvet.ref.htm> <Hexapoda> Johnson, C. G. 1941.
The ecology of the bedbug, Cimex lectuiarius L., in Britain. J. of Hygiene, Cambridge 41: 345-461. Legner, E.
F.
1995. Biological
control of Diptera of medical and veterinary importance. J. Vector Ecology 20(1): 59_120. Legner, E. F.. 2000.
Biological control of aquatic Diptera. p. 847_870. Contributions
to a Manual of Palaearctic Diptera, Vol. 1, Sci. Herald, Budapest. 978 p. Matheson, R. 1950. Medical Entomology. Comstock Publ. Co, Inc. 610 p. Mayans, M. V., A. J.
Hall, H. M. Inskip, et al. 1994. Do bedbugs transmit hepatitis B? Lancet 3453: 761-763. Olesen, Jacob. 2017.
Bed Bug Bites-Pictures, Treatment & Prevention. http://www.bedbugsbites.net/. Reinhardt, K. &
M. T. Siva-Jothy. 2007. Biology of bed bugs (Cimicidae). Ann. Rev. Entomol. 52: 351-374. Ryckman, R. E., D. G. Bentley & E. F.
Archbold. 1981. The Cimicidae of the Americas and Oceanic
Islands: a checklist and bibliography. Bull. Soc. Vector Ecologists: 6-93-142. Service, M. 2008.
Medical Entomology For Students.
Cambridge Univ. Press. 289 p Usinger, R. L. 1966.
Monograph of Cimicidae (Hemiptera-Heteroptera). Thomas Say Found, Vol. 7, Maryland: Ent. Soc. Amer. Venkatachalam, P. S. & B.
Belavady. 1962. Loss of haemoglobin iron due to excessive
biting by bed bugs: a possible
aetiological factor in the iron deficiency anaemia of infants and children. Trans. Roy. Soc. Tropical Med. & Hygiene 56: 218-21. Weidhaas, D. E.
& J. Keiding. 1982. Bed bugs.
Mimeo. document WHO/VBC/82.857.
World Health Organization, Geneva. |